BOSTON, Feb. 3 - Some women call it "the mental-pause" -- a seeming forgetfulness as they approach the age of menopause.
But instead of having short-term memory problems, women of perimenopausal age who are feeling stressed by the vicissitudes of life may actually have temporary short-circuiting of their ability to encode or learn new information, reported researchers at the International Neuropsychological Association meeting here today.
"This is not what most people think of traditionally when they think of memory loss," said Mark Mapstone, Ph.D., an assistant professor of neurology at the University of Rochester in Rochester, NY. "It feels like a memory problem, but the cause is different. It feels like you can't remember, but that's because you never really learned the information in the first place."
Dr. Mapstone and co-author Miriam Weber, Ph.D., who see patients at the university's memory disorders clinic, said that they are seeing increasing numbers of middle-age women who complain of forgetfulness.
"We see a lot of women who are afraid they are losing their minds," said Dr. Weber, a senior instructor of neurology, who presented results of a small study. "A lot of women complain that their thinking or their memory isn't what it used to be. Their big fear is that it's early Alzheimer's disease."
Their findings support those of a study published in Neurology in 2003, in which researchers from Rush-Presbyterian-St. Luke's Medical Center in Chicago found that "transition through menopause is not accompanied by a decline in working memory and perceptual speed."
The Rochester team recruited 24 perimenopausal women between the ages of 40 and 60. They used the World Health Organization definition of perimenopause, which is based on self-reports of menstrual cycles and included any changes in menstrual cycles with at least one cycle over the last 12 months.
Women with significant histories of neurological or psychiatric disorders and those who were taking hormone replacement therapy were excluded from the study.
The volunteers were subjected to a comprehensive battery of standardized tests, which included instruments measuring cognitive function, mood, and psychosocial and health status at a uniform time in their menstrual cycle (between menstrual cycle days four and seven, the early- to mid-follicular phase).
The investigators also measured blood levels of estrogen and follicle stimulating hormone on the day of the cognitive assessment.
"The majority of women in the study reported some degree of memory decline, and some reported this to be of moderate severity," the investigators noted.
All 24 women reported some symptoms of mood disruption, and 15 had symptoms of mild to moderate depression and/or anxiety, but none met clinical criteria for a mood disorder.
Yet despite the prevalence of memory complaints and mood problems, the investigators found that only one of the women had clinical evidence of memory impairment, although several women performed lower than expected on cognitive measures.
"We found a significant relationship between mood state, memory complaints, and encoding, and between mood state and E2 levels," they reported. "These data suggest that mood state may significantly influence the ability to encode new information and the subjective experience of memory loss during perimenopause."
The investigators used the example of a physician who tells a patient that there is something seriously wrong with her and then launches into a clinically detailed explanation, they said. The patient is more likely to focus on the words "seriously wrong" and forget to take in the rest of the information.
"When people spread their attention thin, it's difficult to encode new information," Dr, Mapstone said. "When they're worried or anxious about being late for work, or the problems of an aging parent - that sort of stress can rob your attentional resources and impact your ability to encode information properly."
This phenomenon isn't limited to perimenopausal women but can occur in any man or woman with symptoms of anxiety or depression, he added.
"What characterizes these women is that they're being pulled in a lot of different directions," Dr. Weber said. "Many work -- they have careers, aging parents, children. Then they're going through this dramatic hormonal change."
The researchers acknowledged that the small size of the study sample limits applicability of the data to the general population. They recommend a large scale longitudinal study of the relationship between mood and cognition in women making the transition through menopause.
"If these results are replicated in a larger sample of women, they may help alleviate concerns about subjective memory lapses in perimenopausal women," they wrote in the study abstract. "In addition, these results may inform health care providers of the importance of mood state and its influence on subjective cognitive complaints and objective function during perimenopause. A thorough investigation of mood state may be a first line approach to complaints of memory loss in these women."